Types, distribution and main controlling factors of volcanic rocks in Tahe area

Abstract：Based on core observation, geochemical exploration and a comprehensive analysis of logging and seismic data, the authors hold that that two types of volcanic rocks, i.e., dacite and basalt, occur in Tahe area of Tarim basin， that fissure eruption，extrusion and overflow made up the main forms of volcanic eruption，and that lava flow resulted in the formation of extensive volcanic rocks in Tahe area. The distribution of volcanic rocks is characterized by gradual thinning from southwest to northeast，controlled by the following factors: ① in salt body covered area and its vicinity, the activity of salt body during late Hercynian movement significantly controlled the shape and distribution of the overlying volcanic rock, as evidenced by the facts that the residual volcanic rocks are mainly found in salt-edge sags and the south wing of the area covered with salt body and that these rocks are thickest in sags between salt bodies and thinnest in the salt bulge area which experienced uplifting and erosion; ② the distribution of the volcanic rocks in the north of the study area is mainly controlled by the basement fractures; ③ the volcanic rocks in the southern slope area of the salt body might have been derived from lava overflowing at the center of Tarim basin